"Sadly, a lot of the underpinnings of transhumanism are based on a sort of blind-men-at-the-elephant thinking—people assuming that because it can be imagined, it must be possible. Transhumanism is particularly associated with figures in computer science, which is a field that is in some ways more math and art than a true experimental science (...)In fact, though transhumanists strenuously deny it, a great number of their arguments are strongly faith-based — they assume because there are no known barriers to their pet development, that it's inevitably going to happen. Seldom is the issue of unknowns — known or otherwise — factored into the predictions."- 
How Alcor, a crionics firm exercise due diligence.
"Within minutes of taking custody of the body, the bumbling Alcor team began experiencing a series of equipment failures. A temperature monitor didn’t work because, as it turned out, the batteries were dead. Shortly thereafter, their expensive mechanical chest-compression device stopped functioning. Then, having moved Suozzi’s body into a tub of ice, the Alcor team realized they’d forgotten to bring along a key piece of cooling equipment. Alcor’s after-action report, compiled from the haphazard “free-form” observations of an unnamed but “experienced” observer, determined that such mistakes could in the future be remedied by “the use of a checklist.” Now there’s a thought."- 
Transhumanism is an intellectual and cultural movement with the idea that humanity is capable of and should fundamentally alter the human condition with the use of emerging technologies, and make these modifications widely accessible. These modifications of the human condition are the elimination of aging and the enhancement of intellectual, physical, and psychological capabilities. Transhumanism is something we should aspire to technologically.
How plausible is transhumanism? In the 1930's many sensible people were sure human beings would never get to the moon and that was just one of many predictions that turned out incorrect.  We do not know one way or the other what will become possible in the future and many predictions are speculative.
Technologies of interestEdit
Another emerging technology that is being developed today is genetic engineering. In the future, humans could use it to modify their own genotypes, and therefore increase their physical and cognitive ability.
Another emerging technology of interest is nanotechnology. Nanotechnology could allow damage to the body to be repaired on a microscopic level. Nanotechnology also allows for the development of nanometerials such as carbon nanotubes.